As a high-speed, large-capacity communication system is demanded in a future generation communication system, an increase in the transmission efficiency of a system using a proper channel encoding scheme is an indispensable factor to improve system performance. However, a mobile communication system may generate errors caused by noise, interference and fading according to a channel environment during data transmission, thereby losing information data.
To reduce the loss of information data caused by the occurrence of an error, a variety of error correcting coding schemes are used according to the characteristics of channels, and thus the reliability of the mobile communication system can be improved. Error correction codes used for the error correction coding schemes may be broadly classified into two types according to a channel code generation method. That is, the error correction codes may be divided into codes generated by an algebraic method, such as Bose Chaudhuri Hocquenghem (BCH) codes and Reed Solomon (RS) codes, and codes having a tree structure of a bipartite graph form, such as convolutional codes, turbo codes and Low Density Parity Check (LDPC) codes. The codes having the tree structure have been used in many systems because they are very suitable for real-time decoding of high-capacity and high-speed data due to a relatively simple structure and excellent performance of an iterative decoding algorithm.
In particular, a Tail Biting Convolutional Code (TBCC) has been adopted as standard in many communication systems due to a simple structure and superior error correction performance and has attracted attention as an error correction code for a control channel in a recent standardization process of the Institute of Electrical and Electronics Engineers (IEEE) 802.16m.
A Secondary Fast feedBack Channel (S-FBCH), which is an uplink control channel, is used in the IEEE 802.16m standard. However, the S-FBCH has problems of inability to allocate bits for an additional Cyclic Redundancy Check (CRC) in a system because fewer resources are allocated thereto. Further, in situations where the presence/absence of signals should be determined according to a BandWidth REQuest Channel (BW-REQCH), there are no methods for efficiently determining the presence/absence of signals. Therefore, techniques for checking the reliability of decoded data for those channels are needed.